Those skilled in the computer-image-generation arts are well acquainted with the method of rendering a computer-generated image by dividing a display screen into pixels, and possibly further dividing each pixel into subpixels, before determining which of the pixels (and subpixels) lie inside each of the polygon surfaces to be shown on the display screen. The pixels/subpixels which lie inside the surface are subsequently assigned a color based upon the attributes of the surface to be displayed. Thus, those skilled in the art well know the methods for predetermination of inclusion or exclusion of a particular pixel/subpixel in a polygonal surface of the image. It is somewhat more difficult to determine which pixels/subpixels of a display screen are occupied by a portion of a feature, where a such a display circular feature is not only defined by its centroid (center position) and a color attribute, but also has a non-zero radius. While the centroid describes the X, Y, Z position of the feature center in the display environment, the radius describes the size of the feature. It is well known to transform, project and scale the centroid position to determine the I, J position (where I is the vertical-direction image screen coordinate position and J is the horizontal-direction image screen coordinate position). However, methods have hitherto been unavailable in this art for transforming the non-zero circular feature radius and for determining whether a pixel/subpixel is interior to the feature. It is therefore highly desirable to provide a method for determining the radial extent and inclusion/exclusion of a pixel/subpixel of a CIG display portion within a circular feature.